How Cats Age: A "Cat Years" Calculator

The cat years calculator below converts cat age to human age or vice-versa. You can also place it on your own website or blog if you have one (especially nice for cat or pet-related websites).

Cats and Cat Years Conversion

Converting between cat years and human years isn't as simple as using a factor of 7 (as some people erroneously think with dogs, and sometimes cats). The main reason is that cats mature quickly in the first couple of years of life. To convert cat age to an equivalent human age, an accepted method is to add 15 years for the first year of life. Then add 10 years for the second year of life. After that, add 4 years for every cat year. This means that by year two, a cat has matured to about the same as a 25 year old human.

So it isn't terribly complex, but you would have to do some figuring on paper or in your head. That's where the cat years calculator below comes in handy, which uses the above formula.

Not everyone agrees on the same conversion formula. For a slightly different calculation, the Cat Bible, a book by Tracie Hotchner, provides the following list:

1-month-old kitten = 6-month-old human baby

3-month-old kitten = 4-year-old child

6-month-old kitten = 10 human years old

8-month-old kitten = 15-year-old human

A 1-year-old cat has reached adulthood, the equivalent of 18 human years

2 human years = 24 cat years

4 human years = 35 cat years

6 human years = 42 cat years

8 human years = 50 cat years

10 human years = 60 cat years

12 human years = 70 cat years

14 human years = 80 cat years

16 human years = 84 cat years

Because you can look at the conversion in two different ways, it can be somewhat confusing.

First Perspective: If we assume the maximum age of a human is 100 years old and put that into the calculator formula below, it indicates the equivalent age of a cat (that is, the assumed maximum age of a cat) is 20.8 years. So if you are 100, we can say you are "20.8 cat years old".

Second Perspective is like the Cat Bible above, which says if your age is, for example 16 years, then your cat is nearing the end of its life and is like a human that is 84 years old, so we can say you are "84 cat years old" or for comparison with the first perspective, if your age is 100 years you would be roughly "500 cat years old".
See the difference? Which method do you prefer? In the calculator below we've used the first perspective.

A few random facts: the longest-living cat was 34 years old according to some sources. The Siamese and the Manx breeds are the longest-living cats on average. And keeping your cat indoors typically doubles its lifespan!